The code won't but the spec/format can. What you do is have a third party look at the code. They need to identify a high-level description of what it does, what inputs the format takes, what outputs it uses, the storage format, and so on. Precise enough for someone else to implement it from scratch with likely compatibility. Yet, not copying the code itself and maybe not even copying the implementation strategy. Should avoid GPL tainting.
Even if someone wants to sue over it, I'd say that legal battle is worth fighting because this is similar to how FOSS makes stuff compatible with proprietary software/protocols: reverse engineering their function to make a separate, compatible implementation. Knowing how important that is, I doubt even the zealots would sue someone using above methodology knowing it could set a precedent which might be used against them.
Even if someone wants to sue over it, I'd say that legal battle is worth fighting because this is similar to how FOSS makes stuff compatible with proprietary software/protocols: reverse engineering their function to make a separate, compatible implementation. Knowing how important that is, I doubt even the zealots would sue someone using above methodology knowing it could set a precedent which might be used against them.